a) Sources and types of infection, growth of microbes. nosocomial infection.
b) Factors affecting growth of specimens, transmission of microbes.
c) Cycle of transmission of infection Explain using principles in collecting portals of entry, exit, modes of charts specimens transfer.
d) Reaction of body to infection, mechanism of resistance.
e) Collection of specimens.
DEFINITION
(1) Infection :- Pathogen multiplying in or on the body of a human or animal and causing a reaction in any part of the host’s body is called an infection. (Pathogens (such as bacteria, virus, fungi etc) enter and multiply in as on the part of the body of host it is called infection)
(2) Cross infection:- If infection occurs between two different hosts, then it is called cross infection.
(3) Auto infection :- If infection occurs between two parts (body part) of the same host, it is called Auto infection.
(4) Re-infection :-
Re-infection of the same type of organism in the same person is called re-infection.
5) Primary infection:- The first infection is called primary infection
(6) Secondary infection: Secondary infection:-
A person suffering from a disease caused by a micro-organism of another type is known as secondary infection, it is called super infection.
7) Mixed infection – An infection caused by two or more types of micro organism is called mixed infection.
8) Acute infection – Acute infection lasts for a short time in comparison. The duration can range from a few days to 2-3 weeks
E.g. measles
9) Chronic infection :- Which lasts for months or years. E.g. Tuberculosis
(10) Subclinical infection :- The effects of this infection are not visible on the body.
11) Nosocomical infection :– Hospital-acquired infection is called nosocomical infection.
(1) Human beings :– The most common source of infection for mankind is the human being himself or the carrier and spreading the infection to another person.
(A carrier is a person who does not show symptoms of the disease despite having pathogens in his body.)
(2) Animals :– Many pathogens can infect both humans and animals. Hence animal can also be a source of infection. Infection in animals is mostly asymptomatic. Such animals act as reservoirs of human infection to maintain parasites in nature. Hence it is called reservoir host. The infection that spread from animal to human is called zoo noses.
Bacterial Plague from rats
Viral – Rabies from dogs
Protozoal Leishmaniasis from dogs
Helminthic hydatid disease from dogs
Fungal – Zoophilic dermatophytes from cat and dog.
(3) INSECTS :– Arthropod born diseases are spread to humans by blood-sucking insects. Mosquitoes, Ticks, Mites, Flies, Fleas transmit a Lice infection, it is called “Vector”.
Transmission can be mechanical. E.g. Transmission of dysentery and typhoid bacilli occurs from domestic flies. Such a vector is called a “mechanical vector”.
Some other vectors multiply pathogens in their own bodies. Such vectors of biological. is called “vector”.
Eg :- Anopheles mosquitoes
(4) Soil and water :– Many pethogens can survive in soil for a long time. Spores of tetanus bacilli can survive in soil for decades, and can become a source of infection. Similarly, fungi also survive in soil for a long time. Water also becomes a source of infection after being contaminated.
Eg :- Cholera transmits infection with the help of vibrio infective hepatitis virus, or Aquatic vector. Eg :- . Cyclops in Guinea worm infection.
(5) Food
Contaminated food is also an infection of source. The presence of pathogens in food can be from external contamination. E.g. Food poisoning by staphylococcus or pre-existing pathogen
Eg:- Meat can be a source of infection.
Portal of enter is the site of micro organism susceptible host and cause disease condition.
Microorganism can enter through many routes. such as
mucous membrane
Skin
Respiratory & gastrointestinal tract
Uro-genital & placenta
Micro-organism exits in different ways.
And can infect another host.
Nose
Mouth
Sneeze
Cough
feces
Methods of transmission of infection
Pathogen through which it enters from one person to another is called transmission of infection. It has two types,
(1) Direct transmission
(2) Indirect transmission
(1) Direct transmission of infection
(i) Through actual body contact :-
Due to skin to skin contact, contact with the body of a person who is discharging an organism from a patient, another person who has cuts, abrasion, the organism can easily enter that person.
E.g. Trachoma, Gonorrhoea and Syphilis are spread by direct sexual intercose.
ii) Through infected hands
Human hands come in contact with another person or environment, they come in contact with faecal matter. Harmless staphylococcus and streptococcus are permanently on hand. But many times Pathogen also comes to hand. D. T. While handling the host’s urine, body secretions or fecal matter, a person acquires a pathogen in his own body or in another person’s body. Intestinal and respiratory tract diseases are spread by infection hands. Therefore, direct handling of infection materials should be avoided
(iii) Trough Droplets:- A person also acquires infection by inhaling the droplets released by coughing, laughing or sneezing from the speaking of an infected person. The pathogen of Diphtheria, influenza, T.B., Whooping cough, Measles, Mumps is in nasal discharge or saliva.
(iv) Trough Contaminated fomites :- Diphtheria, Trachoma, Small pox, Measles, Pneumonia etc. are spread through eating or drinking utensils, handkerchiefs, towels, clothes, Sputum cups etc. Respiratory, digestive and skin infections also spread from beddings, clothes etc.
(v) From mother to fetus:- (Before birth, congenital inf.) Pathogen can pass from mother to fetus through very thin tissues between mother and fetus. Hence baby is born with infection. E.g. Syphilis, Aids, measles
(vi) Through laboratories + hospitals:– If aseptic techniques are not used with caution, infection can be acquired from laboratories or hospitals. Syphilis, Viral hepatitis, Aids etc. are its examples
.(2) In-direct transmission of infection
Indirect infection is transmitted from one person to another. And the transfer time is usually long.
i) Through contaminated water and sewage :-
As domestic or industrial waste is mostly mixed in the well, lake or river, it is polluted-infected. The pathogen in it enters a person’s body by drinking or using it and causes infection. Since the sewage system adopted there is not safe, infection can also be transferred from it.
As a result of dumping of raw sewage into water, many water born diseases occur.
Examples are Amoebic dysentery, Typhoid, bacillary dysentery etc.
ii) Through food other than milk Food can be infected in different ways. Even today in many parts of the world, polluted water and manure (animal waste) are used for agriculture. Typhoid bacilli and other pathogens and hookworm, round worm can spread in such soil. Spores of anthrax and tetanus can survive in the soil for a long time.
iii)Utensils:- Utensils used in the kitchen may be contaminated with rat faeces. Insects like flies and cockroaches contaminate food.
Milk and water:- Both these elements are used in the preparation of food. Since Jaina is infected, the infection can be transmitted.
Infected milk
Many different substances are made from it. Hence, milk provides a major means of infection transmission. It is difficult to get milk bacteria free even after taking great care. Many bacteria live permanently in the milk duct and tears.
Contaminate containers, atmosphere and flies also do their work. (Streptococcus lactis is responsible for curdling milk.)
Bacillary dysentery, typhoid are examples of this. T.B. and Brucellosis are spread through the milk of infected cows.
(4) Through Air :-
Organisms spread through air. Pathogens from soil, water and human excreta also mix in the air. These germs exist in the air as droplets or dust particles. It causes infection by breathing in a person.
Diseases like Pul kochs, diphtheria spread. That his infection is transmitted.
These droplets often settle on floors, clothes, beddings, uncovered food and milk.
(5) Through vectors :-
Insects such as mosquitoes, flies, fleas, mites and ticks Arthropods transmit infection from one person to another or from animal to human. They are carriers.
They spread by skin inoculation or biting or by depositing infected material on food.
Vector infections are mostly seen in warm climates because there are a large number of insects and infected humans or animals. Vector diseases are transmitted in two ways.
Mechanical transmission
Diseases caused by bacteria are mechanically transmitted.
Insect all flies, cockroaches etc. get food from faeces. As their feet get infected, they deposit infected agents on food.
Biological transmission :-
In the spread of Malaria, Filaria, Yellow fever, Plague, micro-organisms multiply in the insect vector (plague bacilli in Rat flea) and complete the development cycle in the body of the vector.
Nosocomial infection
The most common type of Nosocomial infection
Urinary tract infection (UTI)
Surgical site infection
Gastro enteritis
Meningitis
Pneumonia
Surgical site infection
Any purulent discharge, abscess, cellulitis at the surgical site is seen after one month operation.
Urinary infection :-
Positive urine culture (1 or 2 species) with at least 105 bacteria/mL, with or without clinical symptoms
Respiratory infection.:-
Respiratory symptoms with at least two of the following signs appearing during hospitalization:- cough – purulent sputum – new infiltrate on chest radiograph consistent with infection
Urinary Infections
This is the most common nosocomial infection; 80% of infections are associated with the use of an indwelling bladder catheter. Urinary infections are
associated with less morbidity than other nosocomial infections, but can occasionally lead to bacteremia and death.
Surgical Site Infections
Surgical site infections are also frequent:
the incidence varies from 0.5 to 15% depending on the type of operation and underlying patient status.
Nosocomial Pneumonia :-
Nosocomial pneumonia occurs in several different patient groups. The most important are patients on ventilators in intensive care units.
Other Nosocomial Infections These
These are the four most frequent and important nosocomial infections, but there are many other potential sites of infection. For example:
Skin and soft tissue infections: open sores (ulcers, burns and bedsores) increase the rate of bacterial colonization and increase systemic infection.
Gastroenteritis: It is the most common nosocomial infection in children, where rotavirus is a chief pathogen. Clostridium difficile is the major cause of nosocomial gastroenteritis in adults in developed countries.
Sinusitis and other enteric infections, infections of the eye and conjunctiva. •
Endometritis and other infections of the reproductive organs following childbirth.
Role of Nurses in Prevention of Nosocomial Infections
Nosocomial infections have a very deep impact on the patient.
2/3 of patients are discharged normally in the hospital.
The cost of treatment increases Nurses can play a pivotal role in prevention of nosocomial infections.
Nurse should be familiar with practices to prevent occurrence and spread of infection, including:
Knowledge of proper techniques of catheter insertion and care
Catheterizing only when necessary
Emphasizing hand-washing
Using aseptic technique for catheter insertion
Securing the catheter properly
Maintaining closed sterile drainage
Obtaining urine samples aseptically
Maintaining unobstructed urine flow when dealing with a urinary tract infection patient.
Collection of specimen
The diagnosis of microbial infection is based on the identification of the causative organism or the response of the body’s immune system to the infecting microbes. (Antibodies),
Nurses are responsible for the collection, storage, transportation of clinical specimens (urine, stool, blood, swabs, sputum etc.).
It is also necessary for the nurse to know how to process different samples for the diagnosis of disease.
Clinical material to be processed is conti-
Microscopic examination of unstained material eg. Urine, stool, cell counts etc.
Stained smear examinations eg. Bacteria, viruses, fungi, some parasites.
In vitro sensitivity of bacteria to antimicrobial agent..
Specific non specific antibody response in blood for which we use different processing techniques.
Diagnosis of causative organisms in disease.
Monitoring of progress of disease
Disinfectants antiseptic agent ell efficiency.
Checking the contamination of environment etc.
Collection of specimens.
Each hospital has its own guidelines for specimen collection and handling.
General guidelines:
Before starting antimicrobial (antibiotics) therapy, take a specimen for culture.
Take an uncontaminated specimen as far as possible in a wide-mouthed container. See that the outer side of the container is not damaged by material spill.
Do not come in direct contact with infected material. Especially in suspected or declared cases of HIV and Hepatitis.
Label ma Name, Age, Sex, Ward 4 bed no. Do not forget to mention, and write the date – time of collection. Don’t forget to show “Biohazard” sampler for AIDS and Hepatitis patients
Send the sample to the laboratory in an orderly manner. or store at room temperature,
Keep in mind that air contact does not occur while taking SPECIMEN for culture of anaerobic organism.
Stool specimen
Take the stool specimen directly into a wide mouth sterile leak-proof container
Or take it in a clean and dry bedpan and fit it in a sterile leak-proof container.
Keep the stool specimen cool. Do not use toilet paper to take the specimen
If the stool specimen is to be taken for ova or parasite, collect it immediately and keep it in a preservative.
Rectal swab
Take a swab with a sterile tip from 1 inch above the anal sphincter
Carefully rotate the swab and take it out and send it to transport media
Throat swab
Do not take swab if there is inflammation in epiglottitis.
Tongue depressor Depress the tongue and take swab from between tonsillar pillar and uvula.
Do not touch lips, teeth or tongue
Wound swab
It is collected from the wound so as not to touch the skin or surface.
vaginal swab :-
Under direct vision, vaginal speculum is taken from the affected area of the vagina.
CSF (cerebrospinal fluid)
CSF is aspirated and taken in a sterile container.
Urine for culture and sensitivity test
UTI (Urinary Tract Infection) can be chronic or acute.Infection spreads ascending.
Its sources can be endogenous or exogenous.
Urine usually contains few bacteria.
During infection the number increases greatly, and Pus cells and R.B.C. Also seen.
Most common bacteria that are found in acute UTI are E. coil and streptococcus.
Lab report usually takes 24 – 48 hours.
Chronic UTI is usually caused by Mycobacterium or recurrent infection.
Purposes:
To confirm the diagnosis and
To identify the etiological agent.
Choosing the right Antibiotics therapy
To determine disease progress during and after treatment.
Points to keep in mind:
Patient should not be taking antimicrobial (antibiotics). (7– 10 days before 18)
Obtain catheterization with aseptic technique.
Use of sterile container.
To avoid contact and contamination of urine, take the mead stream specimen directly into the container and close the container tightly.
Send it to the laboratory for testing within 1 hour by doing proper labeling or store it at 4°C temperature.
Take 3 morning sample for culture of Mycobacterium.
Blood sample (venipuncture)
Materials for specimen:-
Requisition form
Antiseptic agent (70% alcohol or 2% iodine) for skin cleaning etc.
Tourniquet
Gloves, syringe, needle
vaccute/blood culture bottle, Incubator
Record & report
Procedure for blood sample
. Place a sheathed needle or butterfly on the syringe.